Simplify the following expression: $z = \dfrac{1}{2y} + \dfrac{3}{8y}$
In order to add expressions, they must have a common denominator. The smallest common denominator is the least common multiple of $2y$ and $8y$ $\lcm(2y, 8y) = 8y$ $ z = \dfrac{4}{4} \cdot \dfrac{1}{2y} + \dfrac{1}{1} \cdot \dfrac{3}{8y} $ $z = \dfrac{4}{8y} + \dfrac{3}{8y}$ $z = \dfrac{4 +3}{8y}$ $z = \dfrac{7}{8y}$